4 Answers
4

Both. Initially you may find that hand sharpening is kind of slow but once you get the hang of it, and realise you really only need to just slightly touch up each tooth, you can be back cutting in about the same amount of time as it takes to swap chains, or even less.

Always take a spare chain. Even if you touch up the working one rather than swap it out, there's always a possibility of damaging the chain, necessitating a replacement.

Back home it's worth looking into the cost of having the chain(s) professionally sharpened, as opposed to the time you're going to take to do a similar job. Also, you should be able to get a bunch of sharpenings for the price of even a mediocre machine sharpener. At least that's how the costing works out where I am.

When you're in the woods, you probably want to spend your time cutting, not doing things you could do back in your shop (or have the hardware store do for you). So I would bring at least at least an extra chain: as many you think you'd need, plus one.

With an extra chain along, you are additionally prepared in case one has a problem that sharpening can't fix.

Hand-file sharpening is a useful skill. If you learn to hand-sharpen your chains, you can do that to all the chains at once back in your garage.

I'd carry a file to hit the chain every once in a while. It doesn't take long. Another option is a battery powered dremel tool with a round stone to sharpen blades. You have to be careful to not grind the teeth wrong.